1. Field of the Invention
This invention relates to dampers and more particularly to fire dampers mounted in ceilings.
2. Description of the Related Art
A major consideration in the design of commercial and residential buildings is the spread of fire and smoke in the event that a fire breaks out within the building. The walls and ceilings within the buildings serve as the primary barriers to the spread of fire and are most effective if they have no breaks or openings.
Most buildings have heating, ventilation, and air conditioning (HVAC) systems that distribute conditioned/heated air throughout the building by air ducts. The ducts carrying either heated or cooled air are directed to various rooms in the building and the air enters the rooms through openings or vents in the ceilings, floors or walls. These openings and vents, however, penetrate the ceiling, floors or walls, providing a hole that reduces the ability to prevent the spread of fire and smoke. To address this problem, dampers are often provided in the ducts or at the openings and vents that allow air to pass when open, but block airflow, flames, and hot gasses when closed. At elevated temperatures (such as in the case of fire) the dampers automatically close, effectively closing the duct and vent holes and restoring the full integrity of the fire and/or smoke barrier.
One type of conventional ceiling damper used in ceilings, can be arranged between components of the ceiling, such as trusses, joists and TJI beams (referred to collectively as “trusses”). The damper is mounted in the ceiling by a hanging arrangement wherein two or more wires, or some other similar hardware, are connected between the top of the damper and a fixed point above the damper. Ceiling material is mounted to the trusses and serves as the ceiling for the room, with the damper mounted between the ceiling and the top of the structure. The output of the damper is disposed in a hole in the ceiling material and the input is coupled to an HVAC system such that air from the HVAC system passes through the damper and into the room when the damper is open.
The damper can be hung in the ceiling using many different methods, with a typical method comprising mounting a horizontal angle or wood support stud between adjacent trusses, near the top of the trusses, with the support stud providing a fixed point for connection. The damper is then hung from the horizontal angle or wood support stud by two or more vertical angles or hanger wires that are connected between the damper and the horizontal support stud.
One disadvantage of hanging a damper in a ceiling is that the ceiling area between the trusses is small. It can be awkward and difficult to install the horizontal angle and wood stud support between the trusses and then hang the damper vertical angles or wires in such a small area. It is also difficult to cut the vertical angles or wires and connect them at the correct length so that the opening of the damper is at the same level as the ceiling material. If the damper is hung at the wrong level, the vertical angles or wire must be adjusted until the hanging height is correct. This can require repeatedly working the small ceiling area between the trusses until the damper is properly installed.